1. Field of the Invention
The present invention relates to a differential device applied to conveyance means such as automobiles.
2. Description of the Related Art
As is known, an automobile is equipped with a differential, which distributes a driving force of an engine to right and left output axles with allowing differential motion between the axles. Some differentials have proper means for limiting or locking the differential motion between the right and left axles under control so as not to lose traction with the road particularly when one of the wheels loses contact with the road.
In certain cases, a solenoid is used to actuate a device for locking differential motion. How to combine the stationary solenoid with the rotating differential and how to properly position the solenoid relative to the differential are technical issues.
A factor of the issues is that, whereas the differential rotates, the solenoid must be stationary. The reason is that otherwise an electric connection with an electric power source installed on a stationary member cannot be established and the solenoid cannot bear reaction force in response to actuation.
Another factor is that a casing of the differential in general requires an appropriate gap relative to the core to reduce magnetic loss and the gap needs to be stable. The casing is generally made of steel which strongly induces magnetic flux from a magnetic core of the solenoid. When the gap fluctuates, energy loss will occur.
Japanese Patent Application Laid-open No. 2007-315583 discloses an art for supporting a solenoid relative to a differential.